Physiology - Ab receptors (Oct/08/2008 )
I am quite puzzled by this after reading up on human genome and Ab receptors:[/size]
If about 10^5 genes are available in the human genome to produce proteins, how can we produce more than 10*10^6 different kinds of Ab receptors(proteins) on B Cells?[size="4"]
-University_Of_Toronto-
QUOTE (University_Of_Toronto @ Oct 8 2008, 07:14 AM)
I am quite puzzled by this after reading up on human genome and Ab receptors:[/size]
If about 10^5 genes are available in the human genome to produce proteins, how can we produce more than 10*10^6 different kinds of Ab receptors(proteins) on B Cells?[size="4"]
If about 10^5 genes are available in the human genome to produce proteins, how can we produce more than 10*10^6 different kinds of Ab receptors(proteins) on B Cells?[size="4"]
One gene codes for one polypeptide, not one protein. Since proteins are made up of polypeptides (quaternary structure) each gene can form a polypeptide. Each of those polypeptides can form a protein structure with one or more other polypeptides to create the final protein. So if you have 10^5 genes you'd have exponentially more proteins that could theoretically be made from those genes depending on which polypeptides are made, where they're made and what kind of cell signaling is going on.
Does that help clarify it a little better? Just have to remember that protein is a general name for a polypeptide or multiple polypeptides (again quaternary structure).
-Rob Umfress-
As Rob pointed out some genes dont code for a whole protein but for a protein subunit only.
additionally there are post translational modifications and alternative splicing.
both these processes increase the number of proteins that can be synthesized.
in the case of the B cells there is also something else. now this will probably blow your mind: every individual B cell in your body has an unique B receptor. you may want to read about VDJ recombination .
-coastal-
QUOTE (coastal @ Oct 8 2008, 05:28 PM)
As Rob pointed out some genes dont code for a whole protein but for a protein subunit only.
additionally there are post translational modifications and alternative splicing.
both these processes increase the number of proteins that can be synthesized.
in the case of the B cells there is also something else. now this will probably blow your mind: every individual B cell in your body has an unique B receptor. you may want to read about VDJ recombination .
additionally there are post translational modifications and alternative splicing.
both these processes increase the number of proteins that can be synthesized.
in the case of the B cells there is also something else. now this will probably blow your mind: every individual B cell in your body has an unique B receptor. you may want to read about VDJ recombination .
It is not entirely correct to say that one gene codes for "one polypeptide" or that some genes code for "part" of a "whole" protein. Protein subunits are typically transcribed from different genes. As for the "one polypeptide" hypothesis, this has been disproven. In fact, one gene can code for many proteins via alternative splicing. Typically, each gene consists of many exons and introns and, typically, each exon codes for a particular protein domain (or part of one). With alternative splicing, these exons can be joined in many different combinations (ie: exon 1, 2, 3, 4... or exon 1,3,4.... or exon 1,4,.....) etc. The final result is many different proteins being produced from one gene structure. Also, while post-translational modifications (such as SUMOylation, phosphorylation, etc.) can occur and can alter the function of a given protein, these modifications would occur on any of the gene products containing a particular sequence and would not result in a different peptide sequence.
-Dr Teeth-